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Individual differences |
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- Main article: Apraxia
Ideational apraxia (IA) is a neurological disorder which explains the loss of ability to conceptualize, plan, and execute the complex sequence of motor actions involving the use of tools or objects in everyday life. Ideational apraxia is a condition in which an individual is unable to plan movement related to an object because he has lost the perception of the object's purpose. Characteristics of this disorder include a disturbance in the idea of sequential organization of voluntary actions. The patient appears to have lost the knowledge or thought of what an object represents. This disorder was first seen one hundred years ago by Doctor Arnold Pick, who explained one specific patient that appeared to have lost their ability of object usage. When using an item such as a comb several errors were produced e.g., combing the hair with the wrong side of the comb or placing a pistol in his mouth. From that point on several other researchers and doctors have stumbled upon this unique disorder. IA has been described under several names such as, agnosia of utilization, conceptual apraxia or loss of knowledge about the use of tools, or semantic amnesia of tool usage. The term apraxia was first created by Steintha in 1871 and was then applied by Gogol, Kusmaul, Star, and Pick to patients who failed to pantomime the use of tools. It was not until the 1900s when Liepmann refined the definition so that it specifically described disorders that involved motor planning rather than disturbances in the patient’s visual perception, language, or symbolism.
Signs and symptomsEdit
Liepmann was the first to actually conduct tests to these patients in his laboratory. These tests are known as multiple object tasks or MOT. The tasks involve more than one object with the research describing a task to the patient and having them execute what was described to them. Liepmann gave the patients all the necessary articles, a candle and a matchbox, which are laid in front of the patient. He then observed the patients to see how they interacted with each object. In the case of the matchbox the patient brought the whole box up to the wick, instead of simply taking one match out. Or he takes the box from the case, removes a match, and brings it up to the wick unlighted. Another example would be that the patient takes the candle and actually strikes it against the frictional surface of the matchbox. As Liepmann watched he was able to witness the discontinuity of the patients actions with everyday objects. He was able to categorize the errors that these patients produced: mislocation of actions, object misuse, omissions, perplexity, and sequence errors.
But what should be noted is that even though these patients are unable to perform simple to multiple tasks with items that are given to them they are still able to accurately identify objects through a few simple tasks. Patients were able to match a given sequence of photographs with the correct label such as: the process of making coffee, buttering bread, or preparing tea. These patients are also able to successfully identify objects when a researcher verbally describes the function of the tool. Another test that was used was matching the appropriate object with its function. Lastly, the final test that shows that these patients completely understand object usage is that they could recognize the actions of a given tool by a sequence of photographs.
Therefore, the defect is not whether the patients have a lack of knowledge in the usage of an object. The patients completely understand the function of each tool. The problem lies in that the patients, when given an object, can not produce the correct function with the tool. The actual execution of a multiple object task is flawed.
Ideational apraxia is a difficult disorder to diagnose. That is because the majority of individuals who have this disorder almost always have some other type of dysfunction such as agnosia or aphasia. The tests used to make an IA diagnosis can range from easy single object tasks to complex multiple object tasks. When being tested a patient may be asked to view twenty objects. They then have to demonstrate the use of each single object following three different ways of presenting the stimuli. The patient must then perform complex test where the examiner describes a task such as making coffee and the patient must show the sequential steps that makes a cup of coffee. The patients are then scored on how many errors are seen by the examiner. The errors of the patients in performing the MOT were scored according to a set of criteria partly derived from De Renzi and Lucchelli.
Two classes of errors are used to develop a diagnosis:
Class I: Sequence errors
- Action addition (AA) is a meaningful action step that is not necessary for accomplishing the goal of the MOT action (e.g., removing the filter of the orange squeezer in order to pour the liquid);
- Action anticipation (A) is an anticipation of an action that would normally be performed later in the action sequence (e.g., blowing the match out before using it);
- Step omission (SO) is an omission of a step of the multiple-actions sequence (e.g., inserting the filter in the coffee machine without pouring some water);
- Perseveration (P) is a repetition of an action step previously performed in the action sequence.
Class II: Conceptual errors
- Misuse (Mis) errors that can be differentiated into two further types:
- (Mis1) the first type of misuse involves a well-performed action that is appropriate to an object different from the object target (e.g., hammering with a saw);
- (Mis2) the second type involves an action that is appropriate at a superordinate level to the object at hand but is inappropriately specified at the subordinate level (e.g., cutting an orange with a knife as if it were butter).
- Mislocation (Misl) which can be further differentiated into two error subtypes:
- (Misl1) the first type is an action that is appropriate to the object in hand but is performed in completely the wrong place (e.g., pouring some liquid from the bottle onto the table rather than into the glass);
- (Misl2) the second type involves the correct general selection of the target object on which to operate with the source object or instrument in hand but with the exact location of the action being wrong (e.g., striking the match inside the matchbox).
- Tool omission (TO) is an omission in using an obligatory tool where the hand is used instead (e.g., opening a bottle without using a bottle opener);
- Pantomiming (Pant) is where the patient pantomime show the object should be used instead of using it;
- Perplexity (Perpl) Is a delay or hesitation in starting an action or subcomponents of an action;
- Toying(T) consists of a brief but repeated touching of an object or objects on the table.
As the examiner observes the patient for each task they mark off which errors were committed. From this criteria the examiner will be able to focus on severity of the dysfunction. It is important to express that the motor movement is not lost in patients with IA. Yet, at first glance their movements may appear to be awkward because they are unable to plan a sequence of movements with the given object.
The cause of IA is still somewhat of a mystery to most researchers. That is because there is no localized focal point in the brain that shows where this deficit will occur. Since 1905 Liepmann proposed a hypothesis of an action processing system that is found in the left hemisphere of the brain, which is dedicated to skilled, motor planning that guides the movement of the body. Yet, he still was never able to produce two patients with the same brain damage that showed ideational apraxia. The major ideas of where IA is found are in the left posterior temporal-parietal junction. Possibly damage to the lateral sulcus also known as Sylvian fissure may contribute to an individual’s deterioration of object recognition. Another possible area of damage leading to IA is the submarginal gyrus, which is located in the parietal lobe of the brain. Overall, IA is an autonomous syndrome, linked to damage in the left hemisphere involving semantic memory disorders rather than a defect in motor control.
Several severe injuries or diseases can cause IA in a wide range of patients. Alzheimer’s patients are the largest cohort groups that express IA. Other groups that are often seen with this dysfunction are stroke victims, traumatic brain injuries, and dementia. Interestingly, the damage is almost found in the dominant hemisphere of the patient. With that said many of these victims have the damage localized to their left hemisphere.
Ideational apraxia is characterized by the mechanism that the patient loses the “idea” of how they should interact with an object. Norman and Shallice came up with the dual-systems theory of the control of routine and willed behavior. According to this theory one system –contention scheduling is responsible for the control of routine action, while – supervisory attention is able to bias this system when willed control over the behavior is required.
Contention scheduling is a complicated set of processes that involve action schemas. These action schemas are what are used in the sequence of actions involved in making a cup of tea and situation specific factors such as whether a glass of lemonade is too bitter. Even simple tasks need the monitoring of goals: e.g., has sugar been added to a cup of coffee.
But as we learn new activities we are also learning new schemas. We all know how to open a jar of jelly or how to light a match. Schemas are needed in everyday life because they give purpose and goal to our behaviors. In each schema there are subgoals or components that make up the schema. An example would be the schema of lighting a match. There are three subgoals found in this schema: holding the match, holding the matchbox, and holding a lit match. More subgoals could be applied but those are the most obvious when the overall goal wanted is to light a match. That is why schemas form a hierarchy, with the more complicated and complex action sequences corresponding to high level schemas and low level schemas correlating with simple single object tasks.
As said earlier from Norman and Shallice the other component used in voluntary action is supervisory attention. Schemas cause the activation of behaviors; the greater the excitation of the activity the more easily it is to achieve the subgoals and complete the schema. Either top-down fashion activates schemas, where intentions are governed by some type of cognitive system, or by bottom-up fashion where features or an object in the environment trigger a schema to begin. The bottom-up feature is what is seen in ideational apraxia because an object appears to capture the attention of the patient. However, the schema that corresponds to the object cannot be fulfilled. For some reason there is a disconnect in the brain that does not allow the individual to produce the sequence of actions that they know should be happening with the object that is in their visual pathway. It is this area that is still an area of ambiguity to physicians and researchers alike. They are not sure where in the brain the action schema pathway is severed.
Ideational apraxia at the moment has no real recovery. However, Occupational/Physical Therapy may be able to slow the progression and help patients regain some functional control, with the treatment approach being the same as that of ideomotor apraxia. The onset of this disorder is established because of damage to the brain. The only real recoveries seen are found in stroke patients or young patients. The reason for this occurrence is that plasticity of the brain allows for these damaged regions to remap themselves. Therefore, as the patients develop new behaviors to cope with their apraxia their brain’s functioning neurons are able to grow over the areas of dead or damaged cortical tissue.
In some cases the apraxia just vanishes as fast as it appeared. In those cases the patients were not diagnosed with a severe impairment such as traumatic brain injury or Alzheimer. This disorder is becoming a major problem in nursing homes because as the disease progresses and becomes more severe their apraxia worsens. It reaches to the point that patients are unable to feed themselves because of not being able to use simple utensils. Everything must be done for the patients because they have no recollection how objects should be properly used.
With the help of brain imaging such as fMRI, EEG, and PET scans and more research, this disorder may be localized to a specific area of the brain. From that point, new therapies could be developed to help with patients cope with their disorder.
- ↑ Binkofski F, Fink G. (2005). Apraxias. Nervenarzt 76 (4): 493–509.
- ↑ Buxbaum LJ, Schwartz MF, Montgomery MW (1998). Ideational apraxia and naturalistic action. Cognitive Neuropsychology 15: 617–43.
- ↑ 3.0 3.1 3.2 Fukutake T. (2003). Apraxia of tool use: An autopsy case of biparietal infarction. European Neurology 49 (1): 45–52.
- ↑ 4.0 4.1 Zadikoff C, Lang AE. (2005.). Apraxia in movement disorders.. Brain 128 (Pt 7): 1480–97.
- ↑ 5.0 5.1 5.2 Hanna-Pladdy B, Rothi LJG. (2001.). Ideational apraxia: Confusion that began with Liepmann.. Neuropsychological Rehabilitation 11: 539–47.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Cooper RP (2007). Tool use and related errors in ideational apraxia: The quantitative simulation of patient error profiles. Cortex 43 (3): 319.
- ↑ 7.0 7.1 7.2 7.3 Rumiati RI, Zanini S, Vorano L, Shallice T. (2001.). A form of ideational apraxia as a selective deficit of contention scheduling.. Cognitive Neuropsychology 18: 617–42.
- ↑ Motomura N, Yamadori A. (1994). A CASE OF IDEATIONAL APRAXIA WITH IMPAIRMENT OF OBJECT USE AND PRESERVATION OF OBJECT.. Cortex 30 (1): 167–70.
- ↑ Platz T. (2005.). Apraxia — neuroscience and clinical aspects. A research synthesis.. Nervenarzt 76: 1209–+.
- ↑ Ebisch SJH, Babiloni C, Del Gratta C, Ferretti A, Perrucci MG, et al. (2007). Human neural systems for conceptual knowledge of proper object use: A functional magnetic resonance imaging study.. Cerebral Cortex 17 (11): 2744–51.
- ↑ 11.0 11.1 Chainay H, Louarn C, Humphreys GW. (2006). Ideational action impairments in Alzheimer's disease. Brain and Cognition 62 (3): 198–205.
- ↑ Unsworth, C.A. (2007). Cognitive and Perceptual Dysfunction. In S. B. O’Sullivan, & T. J. Schmitz (Eds.), Physical Rehabilitation (5th Ed.) (p.1182). Philadelphia: F.A. Davis Company.
Symptoms and signs: Speech and voice / Symptoms involving head and neck (R47–R49, 784)
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Speech disorder · Apraxia of speech · Auditory verbal agnosia · Dysarthria · Schizophasia · Aprosodia/Dysprosody
Specific language impairment · Thought disorder · Pressure of speech · Derailment · Clanging · Circumstantiality
Developmental dyslexia/Alexia · Agnosia (Astereognosis, Prosopagnosia, Visual agnosia) ·Gerstmann syndrome ·
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